Sagarin's ratings are largely based on score differential, which is logical on the surface. But it ignores how teams are winning or game-planning.
Brian Kelly is content to get the win, so ND often goes into the equivalent of milking the shot clock once they get the lead, depending on the defense to win the game. Other teams keep their foot on the gas pedal and, when it works, runs up the score.
Sagarin's system would work better if he, say, added 20 points to each margin of victory for the winning team to make wins more important. So a 1-point win would be credited with a 21-point win and a 20-point win would be a 40-point win.